For the most part pumps and compressors utilise a mechanical action so as to force an admitted fluid drawn into the system to increase its velocity which is then converted into pressure or alternatively a pumping action.
Typically compressors and pumps based around a piston connected to a crank has the piston reciprocating in the cylinder and the reciprocating action results in pumping fluid which passes into the cylinder. The pump is typically electrically powered, for example by a motor or even in some cases internal combustion motors and so forth.
As the person skilled in the art is well aware one disadvantage of this type of pump is that pumping occurs only when the piston is in the compressive stroke. When a piston is in the drawdown stroke, no pumping occurs as the drawdown stroke is required to suck additional fluid into the cylinder or housing.
Therefore, half the action of the piston does not contribute to the pumping action.
There are a variety of other problems with such arrangements not the least wherein the piston has a short stroke and this results in increased wear and tear on the pump. As is to be expected these types of piston pumps generally suffer from excessive noise levels making them unsuitable for many applications.
While there are alternatives to piston based pumps and compressors for the most part these centre around rotary volumetric designs, typically with radial vanes driven by an electric motor. These kinds of pumps and compressors draw fluid from the atmosphere through an intake opening directed to a pressure tank through a minimum pressure valve which opens only when a predetermined minimum pressure has been reached within the compressor unit or pump apparatus.
One of the main disadvantages of rotary volumetric type based compressors and pump apparatus is the intermittent operation type control system which means that the operation of the electric motor is suspended when the pressure reaches the upper limit value. While this may reduce electric power loss and improve consumption of the arrangement, since the motor is started over again and again from the stationary state, when the pressure falls thereafter it is impossible to promptly supply compressed air or a pumping action when required.
The present Applicant is the owner of international patent application no. PCT/AU2010/001515 “Fluid compressor or pump apparatus” relating to an arrangement that overcomes some of the abovementioned problems. Whilst effective, the need for a still further improved pump and/or compressor arrangement has been recognised.
It is therefore an object of this invention to provide a fluid compressor and/or pump apparatus which overcomes at least some of the above mentioned disadvantages. Further objects and advantages of this invention will become apparent from a complete reading of the specification.
From hereonafter throughout this specification the use of the word compressing is to be considered synonymous with the ability to also pump therefore while the apparatus described throughout this invention may relate to the compressing of a fluid, it is to be appreciated by the person skilled in the art that the apparatus defined is equally capable of pumping fluid. In addition, reference to the word “fluid” is intended to be encompass air, gas, gaseous mixtures, liquids, or any other medium which may require compressing and/or pumping.